It is common for motor vehicles with internal combustion engines to have a tachometer for indicating the revolutions per minute, or RPM, of the engine crankshaft. It is also common for the dial face of the tachometer to include a red-colored strip that coincides with an RPM range that is at and above the maximum rated RPM for the engine. The lowest RPM represented by the red-colored strip is commonly called the engine redline.
It is also common for a particular model of motor vehicle to be offered with several different engines, with each engine having a different redline RPM. For example, a V8 engine may be offered in vehicle and have a 5500 RPM redline; while a V6 engine offered in the same vehicle may have a 6000 RPM redline. Since the engine redline must coincide with the redline region printed on the tachometer face, the vehicle manufacturer must design and assemble two different tachometers to coincide with the two engine redlines offered in the vehicle. In addition to the effort of designing the tachometers, the vehicle manufacturer is faced with the expense of maintaining inventories of different tachometers, and is also faced with the possibility of undesirably building a vehicle with a mismatched engine redline RPM/tachometer combination.